Electrostatic metering apparatus



Jan. 6, 1942. T. A. RICH 2,269,225

ELECTROSTATIC METERING APPARATUS Filed Deo. 2l, 1938 2 Sheets-Sheet lJuf/omer 4//0 Nol/45a- 'Ecreosmnc /Ms'reu/VENT PLATES DAN/#2 Inventor:Theodore .Rich

b 'J/w/y NL; His Attovnemg.

Jan. 6, 1942. T, A. RICH 2,269,225

ELECTROSTATIC METERING' APPARATUS Filed Dec. 2l, 1938 2 Sheets-Sheet 2Figli.

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2000 v a Q d /500 k 300 n) y) U4 /000 200 200 e E I t @e e rwveh or. 0aw @V d0VV /ap Theodore A.F\|ch,

by www@ a fo I ma i His Attorney.

Patented Jan. 6, 1942 UNITED vSIAI'NES f fr Y y zamls... ELECTROSTATICAllllALRlYIISL TheodoreA. Rich,l jSchenectadjs.'N assigner.to.A

General Elctre 'Compan tus: that can.. byrsimple.changesl inconnecti'onsy be;y used forL :measuring different .Aquantities',. fsuchas; ,the reactive: powem1-voltssr and ampereseover differentmeasurementzranges'..A I

In carrying my invention into eiiecmkemplo ahook-ontransformer..arrangementto obtain a voltage proportional; tov currentand.. 'a'. hookzfon resistance element,v for.'` obtainingz-- measurementvolt-ages.; These voltages excite.; an" electrostatic meterwhich is *apart of and.,is.supported;by the hook-on transformer equipment. The'ydeflection of the moving part of the electrostaticmeter` is opposed byan adjustable spring and measurements are taken by noting the extent' ofspring adjustmentJ necessary" to maintain the deflection atzazerogvalue. A; light beaml=indicator `particu larly 'designed for goodvisibility under the rather awkward measurement conditions encounteredvis used to indicate such zero deflection, and., the extent ofadjustment of ti'1e'springy is'registered onan'. easily-:read scale.Insulatinghandle means are provided=for makin-g1 the various connectionsendif-adjustments in order toprotect the user' of the equipment fromdangerous voltages: These and otherf features of'the invention; willbem'ore fully described in connection with the accompanying drawings inwhich Fig. 1 represents a face view ofthe transformer and meterassembly, Fig. 2 is a perspective view ofthe meter elements andalsoindicating the connections'for metering single phase reactive voltamperes hereinafter referred to asvars, Fig. 3 isia sectionalend viewmatic-representation ci the'connectionsusedf'for diag-ram-,maticallyrepresent?- 4the connections*for measuring 'amperes 'i and``A voltsrespectively.vv Figi of themeter ibo-xJ and"r meterswitch-ing means'containedf-thereon;v and Figi' 1-2'" shoWscalibration curvesusedforinterpolating the: instrument reading terms ofJ theL quantitiesnriea-su'red` TheJ features-ofimyrinvention* which are/believed tabsnovel and-ff patent-able-will1- b'es'po-inted out in the claimsappendedrlferetob y 'Ihe main partfof'i the'V equipment preferablyytakesftheu form shown iii-Fig; 1,V andf'comprises a housing," IIJhav'ing=an1 insulated handle I I` extend in'gff'om rits bottom#r and!supporting' batteries- I2 and loel-orr--transforrrnerV apparatus on itsYtop..

If'ord'erthat the transformer apparatusfmay best support the equipmentwhen itishun'gon artransmission sli'nef cable# asrepresented in Fig; 4,ythe transformer apparatus lis-made in two sections Ii3and IM!The-parteci thesel transformer sections whichlareiindicatedby#referencecharacters I3 and Iiiiarel-lam-inatedv magnetic coref'sections rigidlysecured totlief-topfof"`thefihousing I lll'and aregenerally ushapedbwiththeir. open ends faoingIf-ini ,tliel saine horizontal direction.l Theopen'lfendsio these core-sections ar'elfadaptedy tobennechanicaliyolosedfand'partiallymagnetically-I@whichi:arepivotediasiat- I1. to; the bottom ends otitheiU -shapedcorecparts .I 3 and I 4- respectively.. These? transformer; ooneslie;parallel; planes and:have.:their?.stationary1 portions @connectedifbythe housing: and: tietrodr. |81.. Thewhinged. parts areconnectedcbyztheftie nodal 9g Theieorelassemblysmaygbe: opened,.asiindicatediinaFig V3byusing y the hookipartyl ofethetoolshown.in;Fig.rJ7`v to of the transformer with th'e hook thereofpartially open. and also, showing an automatic switch for turning on andoi the lamp employed" in the meter. metering equipmentfas'hookedinfmea,suring-:relaition-with a` high voltage. transmissionzlinea-Eig..5 is an explanatory enlarged view of. one:v of'ythe voltagereducing/resistance sticks shown in' Fig; 4. Fig. 6 illustrates Y'onefofthelead;supportinglips Fig'. 4 isal perspectiveview of thevwhichareprovided' on the equipments: whenever` n necessary or desirable.Fig...7fl is; an insulated tool .for makingrvarious'connections and,adjust;-

'^ diagrams shoving; inward; (mi tiey rodi" I9: using tliegforked corewtthi the hookr20pof1theftool ofi Figi 'Z without danger to theoperator. The insulated handles Il and 22 may be as long as desired.Handles which are from three to six feet long will generally be suitableWhere the operator climbs the pole or tower to hook the meteringequipment in metering position over a cable supported by such pole ortower.

Where the metering equipment is to be used as explained hereinafter, itis desirable that the transformer coupling with the primary conductor 23contain an air gap. This is accomplished as shown in Fig. 3 by providinga spacer 24 of nonmagnetic material at the point where the `hinged partI6 closes on stationary part I4. Although this arrangement is herereferred toas-a-trans- Y former it should be recognized that it worksunder a special set of conditions. The secondary current is negligiblysmall and the secondary voltage equals IwM where I is the primarycurrentLr-f is 21r times the frequency and M is the mutual linductance.Another feature shown in Fig. 3 is an automatic switch having astationary contact 2'| and a movable contact v28 for 4closing a circuitcontaining lamp 29 and dry cells I2 when the apparatus is hung on acable such as indicated at 23, and for opening this circuit againy whenthe apparatus is removed from the cable. This is accomplished by havingmovable contact 2,8 supported on a resilient member 28 which ispositioned so as to be raised b'y the cable 23 to close the contactswhen the apparatus is hooked over and supported by such cable.

The lower stationary limb parts` of the transformer cores have secondarycoils and 26 wound thereon and these coils are for supplying measurementvoltages proportional to line current to the electrostatic meter inhousing l0 and may have different voltage taps and be connected inseries, as desired.

A perspective View of the electrostatic instru-Y ment which is containedin housing I0 isshown in Fig. 2. This instrument comprises a longarmature vane 30 secured on shaft 3I. Near the opposite ends of armature30 are sets of stationary plates 32, 33, 34 and 35. 'Ihe sets of .plates32 and 33 at `one end of the Varmature are on opposite sides of acentral position of the armature vane and the plates of each set areabove and below the armature vane such that the vane may move betweenthem without touching. The arrangement is such as to bring aboutclockwise rotation of 30 due t0 electrostatic attraction between one setof plates and the armature and counter-clockwise rotation of `3ll due toelectrostatic attraction between the other set of plates and thearmature when the diierent parts are charged. The plates and armaturearrangement at the other end is the same. The combination may beconsidered as comprising duplicate electrostatic instruments with theirmoving vane armatures on opposite ends of the vane -3l). If consideredas two instruments they are connected in parallel to produce jointaction. Thus, plates 32 at one end and on one side of the armature areelectrically connected to plates 34 at the other end and on the oppositeside of the armature so that the forces between the armature and thisgroup of plates will all tend to turn the armature 30 in the samedirection. Likewise plates 33 and 35 are connected together in anothergroup and hence will have additive electrostatic torque action on thearmature. At 36 I have provided a permanent magnet damper for thearmature,r andv at 3l' Iv have provided stops to `limit vthe movement ofthe armature to a small angle on either side of its central position.

The electrical connections of the instrument as represented in Fig. 2 isfor the measurement of single phase vars. It is noted that thestationary plates of the instrument are connected across the terminalsof the two current transformers connected in series. Hence a voltage Eiwill exist betwen stationary plates 34 and 35 which is proportional tothe Current in line conductor 23. Owing to the air gap in the magneticcircuit of the transformers as mentioned above inconnection with Fig. 3and the fact that lno current` flows in the transformer secondarycircuit, this voltage Ez' will be nearly 90 degrees fromthe current inline 23, and if it be assumed that the power factor of the single phasepower circuitrep-resented is unity, it will be nearly degrees from thevoltage of the power circuit. A voltage Ev proportional to the linevoltage is impressed between the armature 30 and stationary plates. Animpedance 38 is connected across the single phase power circuit. Thisimpedance is mostly resistance but contains a condenser39 which issufcient to shift the voltage Ev exactly 90` degrees from voltage Ei atunity power factor'. Alead 40 to a tap on this impedance is connected toarmature vane 30 through its/shaft 3|, and a ,connection 4I connects themiddle point of the current transformer circuit to line conductor 23.Hence the voltage Ev is 90 degrees displaced with respect tothe voltageEi between the stationary plates when the power factor of the singlephase circuit is unity.

In the schematic connection diagram of Fig. 8, the.instrument isconnected to measure vars. Thevoltage between 30 `and 321 is equal toyEv-f-Ef ina vector sense. The voltage between 30.and 331 is equal toEv-Ei also in a vector' sense. The electrostatic torque between chargedplates of this type is l dC twat where V is the voltage between .theplates and c lQ d0 is the ratej of change of capacity with angle.Absolute units must be used in evaluating this equation. ,As shown inFig. 1, the net voltage betwen 30, 321 would cause a countercl'ockwiserotation and the voltage between 30, 331 would cause a clockwiserotation. These torques lare proportion-al to the square of the netvoltage or ment of varsthis springiwill usually be arrangedy2,'.i2i69y2'25.

offiv/.hichis representedgat; 60; Thesesreelssmay have a.selffwindingspringf arrangement 6l s. like n to; wind up. whenitopposesothe deilection othe armature. inthe diretioniwhichit deectswhen thecurrent lagsihevoltage.; Inimost cases. the power-factor will belagging andthispuseispre.- ferred. ,OnA leadingipovverrfactors vtheunit. must be.. rotated@ 18.0,? with yrespecta.toi. the;i line; con,.

ductor 435 in Figi. 4:., .The spiral.. spring.' has.; its n inner.end.;l connected tp;shaft 3]' andcits-.outer endgconnectedsto a .pin43.5.arrangedtdbefadjusted about.A shaft. 3 I..thi1ough'.aigearr train4:4, .a shaft: .45.. and a.. thumb piece- 45 byl: means. of which ne.adjustment. of'.the.spring...fmay bezhad; The4 gears. and z rods. 46:anda 49.'.are `made` Offinsulating. material. ingiarrangementextendsdown through 4the hol.- low insulating.handle?.v |i|..showrrlin Fig..y1E such that'. the. spring adjustment'. maygbeimade the operatortur-ning.;thumb.A piece.. 45 u.While-ina safel positionwith respect toany high -voltagef line Withwhichy theA instrument mayf beconnected.Sucht adjustmentl of spring- 4.2 in a. direction yto oppose the torqueof" .armature 30 when tending. to deflect` away. from a mid positionalso'movesf apointer L'lfup scale-with` respect tol a scale-lsv rIlhisisaccomplishedthrough the gear train which-branches offthroughfshaft 49.-Measurements are made by increasing the torque of spring 42. toireturnarrnatu'rel3ll-to'.ay zero or midposition andnotingfltheextenteof suchspringk adjustment on Scale- 48.` irl-'terms ofy the actualielectricalmeasurement' or in such -terms as may be quick-ly#interpolatedin varsoil-whatever is being measured. Y

In-v addition to thepa-r-tsdescribedgthe operator needs--anaccuratedevice that 'Wi-llrgive a cleary indication fromseveral feetibelow themeter When the larmature 30 has-been: brought' back to; a midposition.For this purposefIl providejthe lamp 2 9,' light from which may be seenrby theA operator; from-below thev meterI through the glassstrips- 52* or53: Light from-lamp 29 isconducted-byglass, stripf5| wto a centralslit'5ll'inV theend'ofl armature 30.y The-Width of the-slit 5!) isapproximatelyv equal -to thethicknessof52 and53". Themovement'ofthearmature 30is restrained by stops 31- so that-at oneextreme theslotLis-.over the end of 52iandiat the other' extreme overthe end` of 53. The endsof521and 53 near thearmature are veryclosetogether buttheirA far ends are well separated. In use the light;appears to jump from 52. to 53 (perhaps when the armature moves thewidth of the slotllwhich may be 0.020.

Balance is obtained when a slight` motion of 45 will'l s hift the lightback` and forth. In general, the loads will have enough fluctuation sothat the light'will'oscillate back and forth at balance.

The impedance device 38"which is used for obtaining a suitable voltageproportional to line voltage is preferably inclosed'in a long insulatingtube 51 of the form shown in Fig. 5: The upper end lof this tube isprovided with a hook terminal'55 which may be hooked over a highvoltagev conductor and is'threaded to bolt 58' securedr in the top ofthe tube So that by turning the tube 51 the conductor'may'beclampedbetween the hook andi-bolt to provide a rm electricalandmechanical connection. As indicated,v the ybolt is connected to one endof the impedance. The other endo the impedance is connected' to one ormore flexible cables such as shown at 58 and 59 for making otherlineconnections. In orderto. havethese cables longjenough for all purposes`and still' avoidr having them hang' down to the lower handle part of.the insulatedtube51;',any

extra lengthr of 'such' cables is wound' on reel's one The shaftf Mit-of.this ad-ji'lst-- 'zrofwordinate graduations are provided for volts,

that ;,used.y on. the. common Window curtain, roll,l soirthat the cablemay.. bepu1led.- out.. andilallowed torewindi asneedeol.' The-free endsofthercab'les-l 58 and 159i are, provided Withconnecting clips .6%

central portion `of' whichL-.is punched. out to .form an opening.fl'ankedfby the' punched out aps 62h.

llsowanotlfier opening isprovided at 62'0 throughl which the hook 63'..is passed.V Each such'clipZx is provided with a threadedopening..t4;facingv downward into which the.threaded endlt-Sn of. thetool shown in mayI be'screWed-for-the purpose of lifting these clips'.oft of" hoeks.. 63? and transferringethem to s0mek other hook; Thispermits'various connections of the apparatus tobe made andl changedWhiley the circuits are alive Without danger to the operator. ThereWillvalso be a'lexible cable, reel, and/clip Ysecured tothe rear side-ohousing lllior making theconnection 'Hof Fig. 2. Such flexible `cableconnectionfis partially shown at V1H." in Fig. 4. The connection IW ofFig. 2-isl `also indicated in Fig. fl; The device indicatedatf, Fig'.`5,- is al small glow tube inI the in'ipedancel circuit which glows@Whenever the '-impedance 'is'.l connected across la high Voltage line.This'glcw tube-may be'seen inpa- Windowof the tubular housing and servesas fan. indication to the operator as towhetheror not theimpedanceis-alive. a

Fig. 8^-isa; diagrammatic representation ofV the connections of mylapparatus formeasuring 3c vars; and- Fig; 4 israpictorialrepresentation-of the equipment as used for this; connection.In Figi.y 8 thefelectrostatic instrumentis-simplyv indicated by one setof each group ofthestationary, plates designated 32I and 33 separated bythe movableivane armaturell.` For this connection it is assumed that'thephases arejbalancedand that the meter will-measure 1/3`y of. the'B-phasevars.

Fig. Qrepresents the.conn'ectior'isof` the meter for measuring current.In this connectiomfone group of the stationary platesdesignated 33- isconnected to the armature vane 31T, and to one terminalof'thetransformer circuit. The other group ofY stationary. platesdesignatedv 32 is connectedto theotherterminal of the transformercircuit. Thus` a.vo1tage proportionalV to current. will exist` between.plates 32r and armature. 30. A] corresponding.torque` will result. .Herethe. group ofjstationary plat`es33` produces no torque.

Fig. l0 indicates the connection, for measuring voltage.V Here asuitable' part of.. the line voltage is impressed between the armature.and. onefset` of stationaryplates.l The measurementds.. of. courseproportional to the line, Voltage.A Asin Fig, 9,l theset Vof stationaryplates 33f are idle.

To facilitater theinterpretation ofthe reading, of pointer 41 on scale48 forthevariousdiierent measurements that `may be. made `by 'thisinstrument, it' willV be desirable to have the scale calli'- brated inpercent from 0 to 100' and then pro.- vide the. operator with .a chartor charts of the. character shown in Fig, 12. This chart com.-

prises curvesdesignated bolts, amps. and kilovars.. y

The abscissa isfA inv percentand .correspond to .therindicationofpointer 4,1. ondal 481v Threesets;

kilovars and amperes respectively. The curves are simply thecorresponding calibration curves of the meter for the differentmeasurements referred to the 100% scale of the dial 48. If, for example,current is being measured using the connection indicated in Fig. 9 and areading of 50 is obtained, reference to the calibration curve foramperes shows that the current is about '15 amps. Similarly, if vars arebeing measured using-the connection of Fig. 2 and a reading of 50 isobtained, the reactive volt amperes are read olf the kilovar curve andscale and is 190 kilovars. It will be understood, of course, that thesecurve relations are obtained with a particular tap on impedance 38, andthat if this tap point is changed the calibration chart must be changedaccordingly.

As shown in Figs. 8 and 9, the current transformers have different tapstogether with a tap changing switch. This adapts the instrument formeasurements over a correspondingly wide range of primary currentvalues, and when the current transformer tap is changed the reading ofamperes and kilovars obtained from the chart must be multiplied by thechange in current transformer ratio. The tap changing switch for thispurpose and the switches for changing the other connections of theinstrument are shown in Fig. 11. The current transformer tap changingswitch is indicated by reference character 15. This switch willpreferably be mounted on the outside side of housing I as indicated inFig. l, and will have an operating cross bar that may be operated by thetools 20 and 2| of the insulated operating rod of Fig. '7 so as to openand i close this switch in either direction from a safe position. Theswitches for connecting the electrostatic instrument for diierentmeasurements are preferably assembled just above the bottom wall 61 ofhousing I0, and for the uses of the apparatus described will be three innumber and are indicated by reference characters 68, 69 and 10. Theseswitches each have three upper and three lower contacts. The uppercontacts are stationary and connected in parallel to the three ,g

terminals of the electrostatic instrument designated 30, 32 and 33'. Thelower contacts of each switch are insulated from and mounted onresilient supports secured to the insulated wall 61, and are normallyspaced away from their col operating stationary contacts with theswitches open as shown for the switches 68 and B9. Beneath these movablecontact supports there are threaded openings 1I in wall 61 into whichthe tool 65 of the insulated handled tool of Fig. 7 may be screwed. Whenthis tool is screwed in as shown for switch 1|] the resilient support ofthe movable contacts is raised and the switch closed. The movablecontacts of these switches are suitably connected to the currenttransformer tap switch and the voltage terminals of the apparatus asshown so that the Various measurements previously described may be madeby altering the switches. As arranged in Fig. 11, it will be seen thatwhen switch 68 is closed the apparatus is connected to measure linevolts as indicated in Fig. 10. When switches and 69 are closed theapparatus is connected for measuring single phase vars. This connectionis equivalent to that shown in Fig. 3. When switches 15 and 1D areclosed the apparatus is connected for measuring current as in Fig. 9.For the last two connections the current measurement range may be variedby throwing the current transformer tap changing switch 15. The voltagebushing represented at^12, Fig'. 11, is shown in Figs. 1 and 4. Theother voltage terminal 13 of Fig. 11 is on the back side of the housingand hence is not seen in Figs. 1 and 4.

In using this apparatus, the operator ordinarily carries the equipmentupa transmission tower or pole with the hook arrangement of thetransformer open. Then using the insulated handle l I, he hooks thetransformer over one of the lines 23 of the Vhigh Voltage line. Thenusing the insulated tool yof Fig. 7, he closes the hook arrangement ofthe transformer. If only a current measurement is to be taken theimpedance sticks such as shown in Figs. 6 and 4 are .not required. f-If, however, voltage or var measurements are to be made, theV requiredimpedance stick or sticks are hooked Von the transmission line and thenecessary connections made using the insulated tool of Fig. 7.

The circuit of lamp 29 is closed automatically when the apparatus ishooked on the line as explained in connection with Fig. 2. Hence theoperator is ready to take his measurements by tuning thumb nut 45 untilthe instrument deflection has been brought back to zero and reading theindication of pointer 41. Any one or al1 of the measurements previouslyexplained may be made one after the other and the results recorded in anote book after which the apparatus is removed, using the insulatedtools as before, and the apparatus carried down the tower. Hence theapparatus is suitable for making the measurements on high voltage lineswithout danger to the operator and without cutting any lines orinterrupting service. The apparatus is especially adapted for makingtemporary measurements at isolated points on transmission lines where itis impracticable or undesirable to install permanent metering equipmentbut where it is desirable to make measurements occasionally. Theequipment used will include properly marked impedance sticks adapted forlines of different voltages and the necessary calibration charts.

While I have shown and described a particular embodiment of myinvention, modifications thereof will be apparent to those skilled inthe art. I do not', therefore, desire my invention to be limited to theparticular construction shown and described, and I intend in theappended claims to cover all modifications within the spirit and scopeof my invention.

. What I claim as new and desire to secure by Letters Patent of theUnited States is:

1. Portable electrostatic measuring equipment for use on high voltagelines comprising a housing, hook-on transformer means at the top of saidhousing for supporting the apparatus in measuring position on a cable, ahollow handle of insulating material extending downward from saidhousing, an electrostatic measuring instrument in said housing having amovable armature, a spring for opposing the electrostatic torque 0n saidarmature, insulating means extending through said handle for adjustingsaid spring and means observable from below said housing for indicatingthe adjustment of said spring in terms of the electrostatic torque onsaid armature.

2. Portable electrostatic measuring equipment, hook means thereon forsupporting said equipment on a transmission line cable and connectingsuch equipment in measuring relation with such cable, a handle ofinsulating material eX- tending downward from such equipment by means ofwhich 'said' equipment may be Sup- `t1 electrostatic 'measuring instdegrees from the amazes on and removed from measurement rel-ath a cable,sain equip-rnentiinciuding an ''e'n't yhavili'gy a movable armature, anadj-us able'fspifiifg`for'-op- "posing the measurement torque 'onf's'aid rarri-rature, insulating Ir-e'a's ei'ite'n'ding to the 'lowerend-'f said handle i-oradjiisti fg 'in ans fior indicating th'ee'romeasurement posi-tion of-sad ported armature k:ma means ffo'r'indicating itne'egtent of adjustment o`f said v'spring 'in fte'r'insfofthe 'measurement torque lof saidlinstrui-nent.

'3. A'Ptir-"table 'measuring 'ecfuipmnt for use 'on high vvoltag'ecables comprising fa suppoting housing, hook `means on -said housing`'whereby the 'equipment `may ybe Vhooked on Aand supported by one ofthe :cables-of -`a multi-ple-lcable'transmission line, la :halr'id'le ofinsulating r'nf'a't al'extending downward'from said housi'n'g `byfirfr'eafs of which the yequipme'nt"may be Isupportedon and removed fromsuch cable, an eleotros`,t'a'.tic measuring *instrument `-in Esaidhousing hav-ing stationary andfrnovable electrostatic plates, 'animpedance device "in the 'form of fa :stiok-li'lie structure having 'aninsulating handle extending Cfrom Y"one end l'and afhool; at the otherend whereby 'such impedancedevie m'ay be supported by and connected toanother cable lof such transmission line, connections for connectingvsaid impe'danceac-ross such cables, connections for connecting aportion of said impedance across movable and stationary plates of saidinstrument for the measurement of voltage between said cables and a toolhaving an insulated handle to assist in making such connections, wherebysuch equipment may be connected and removed from voltage-measuringrelation with high voltage cables with safety to the operator.

4. Electrostatic measuring equipment for measuring vars on a highvoltage circuit comprising a transformer having a hinged magneticcircuit whereby the transformer may be hooked over a cable of thecircuit to be metered, said transformer having an air gap in itsmagnetic circuit when in measuring relation with such cable, anelectrostatic measuring instrument having opposite sets of stationaryplates and a movable armature plate located between the opposite sets ofstationary plates, means for connecting the sets of stationary platesacross the secondary of said transformer, connections for impressing avoltage proportional to the voltage across such circuit between themovable plate of said instrumentl and the middle point of said secondarytransformer circuit, and means for causing the phase angle of saidvoltage to be 90 voltage across the secondary of said transformer whenthe power factor of said circuit is unity.

5. In combination with an alternating current circuit, electrostaticmeasuring equipment for making measurements on said circuit, saidequipment comprising a transformer for obtaining a voltage proportionalto the current flowing in said circuit, an impedance device forobtaining a voltage proportional to the voltage across said circuit, anelectrostatic measuring instrument, circuit connecting means includingswitches for connecting said instrument to said transformer formeasuring the current of said circuit, for connecting said instrument tosaid impedance, for measuring the voltage of said circuit, andconnecting said instrument to both said transformer and impedance formeasuring .the vars of said circuit, said transformer and impedancebeing designed to produce voltages which are dgre'e's out 'of "phasewhen the-power 'factor of 'fo'rme'r'is A`mounted` 'an electrostaticmeasuring instru/ment `in said vhousing, insulated handle means forfsaid housi'ng and impedance, by meansfof which the apparatus maybeplaced in -nieasurinentrelation with 'and removed from 'a dhighvoltagecircuit with safety to the operator, aridswitching meanson saidapparatus for alternately 'connecting said instrument Ato thetransformer for 'measuring/the ,circuit current, 'tothe impedance 'for"measuring'the circuitvoltage, and vto both thetransformerand impedancefor 'measuring the cir'c'uit vars, ksaid transformer and impedance beingdesigned 'to produce voltages which a`re' 90` degrees displaced when thepower factor ofthe circuit'to be metered is unity.

'7.v Portable j'eflectrostatic measuring equipment for use "on high'voltage circuits, said equipment including a housing, a hook-ontransformer on said housing, said transformer having a pair of hingedcore magnetic circuits spaced apart and secured to said housing nearopposite ends thereof, means mechanically connecting the hinged parts ofsaid cores so that they may be opened and closed as a unit, said coreparts serving for the purpose of removably suspending said housing on acable of the circuit to be metered over which the core parts are hung,which cable then static measuring instrument in said housing having twosets of stationary plates cooperating with a movable armature plate,means for connecting said coils in series across said two sets lofstationary plates, and connections forimpressing a voltage proportionalto the voltage of the circuit to be metered, between said movablearmature plate and a point in the secondary circuit of said transformerin the connection between the secondary coils.

8. In a portable measuring apparatus, a housy ing, a measuringinstrument in said housing, a hook-on transformer on the top of saidhousing, an insulated handle extending from the bottom of said housingby means of which the .housing may be suspended from a high voltagecable by the hook-on transformer with safety to the operator, a lightbeam indicating system for said instrument including a lamp, a supplycircuit for said lamp including a switch for energizing andde-energizing said lamp, said switch'being mounted on the hook-ontransformer and having a movable switching member positioned to beclosed by the operation of hooking said apparatus on avcablexand openedby the operation of removing said apparatus from a cable.

9. In a portable measuring equipment for use on high voltage. circuits',a housing, an electrostatic measuring instrument in said housingincluding a movable armature member, means on the housing for suspendingthe housing on and in measuring relation with a cable of a circuit tobemetered, a lamp in said housing above said instrument, a restrictedlight path from said lamp downward through said instrument and housing,said path including an opening in the movable armature of saidinstrument when said armature is in a zero defiecting position, saidarmature serving to intercept said light path when the armature moves ineither direction from a zero deecting position.

10. In a portable measuring apparatus for use on high voltage circuits,a housing, means on said housing for suspending the housing from a cableof the circuit to be metered, a measuring instrument in said housinghaving a movable armature, connections for connecting said instrument inlmeasuring relation to the circuit to be metered, a spring for opposingthe movement of the armature away from a zero deecting position,insulated adjusting means for said spring extending downward from saidhousing by means of which an operator located several feet below saidhousing may adjust said spring, a pointer connected with saidspring-adjusting means, a scale over Which said pointer moves, saidpointer and scale being visible by an operator located below saidhousing, said pointer indicating zero on said scale when the armature isin a zero deecting 2 position and the spring is adjusted for zeroarmature torque, said pointer moving up-scale as the spring tension isadjusted to retain the armature in a zero deecting position as theinstrument torque increases during a measuring operation, and meansobservable from below said housing to indicate whether or not saidarmature is in a zero deflecting position.

11. Portable measuring equipment for use on high voltage circuitscomprising a housing, a measuring instrument in said housing, a hook-ontransformer having a hinged core on the top of said'housing, a handle ofinsulating material extending from the bottom of said housing, saidequipment being proportioned and designed to be carried up a hightension transmission tower byl an operator and suspended on a cable of ahigh voltage circuit supported by such tower While the operator remainsat a safe distance from such cable, means on the exterior of saidhousing and observable to an operator below said housing for indicatingthe measurement operations of the instrument, switching means on saidhousing and operable by an operator below said housing for connectingsaid instrument for different measurement operations and a tool havingan insulated handle particularly designed for operating said switchingmeans and for operating the hinged core of said transformer by anoperator located below said housing a safe distance away from saidapparatus.

THEODORE A. RICH.

